Oxidizing briquette



Patented Mar. 20, 1934 UNITED STATES PATENT OFFICE OXIDIZING BRIQUETTE tion of Delaware No Drawing. Application March 28, 1932, Serial No. 601,722

4 Claims.

My invention relates to an oxidizing agent, produced in a densely compressed mass, for use as a decarburizing addition to the molten metal bath in the manufacture of steel by the open I hearth process.

At various stages in the manufacture of open hearth steel it is necessary to add an oxidizing agent to the bath to reduce the carbon. The agent heretofore most generally employed has been iron ore, in lump form, of the highest grade and with the minimum of impurities. An ore of this character is not only expensive but, in certain steel producing districts, it is not always available or its cost is prohibitive, and this has 1 necessitated the use of lower grade ores with the consequent addition of a substantial amount of impurities to the bath, which is obviously obiectionable.

The p se of my present invention is'to provide as an oxidizing agent a densely compressed mass of iron oxide which can be made up from products conveniently and economically available at nearly all points where the open hearth steel' is manufactured and which will not only replace the high grade ore but will in effect provide an oxidizing agent superior thereto and made available in the most desirable form and at a materially lower cost.

The oxidizing element selected is iron oxide 80 in the form of roll scale and I propose to compress this light, flaky form of iron oxide into dense masses with an addition of a non-carbonaceous binding agent which will bond the roll scale without adding thereto any appreciable per- 86 centage of impurities which would degrade the iron under treatment in the-open hearth steel furnace.

I have found that roll scale in the form ordinarily available can be suitably bonded by the admixture therewith of three percent by weight of cement and six percent by weight of finely ground open hearth slag. The cement consists largely of inert matter which will not react with or adversely affect the iron bath, and the open hearth slag itself, being normally present in the process, will not involve the addition of any objectionable element not readily controllable under existing practice. The compressed masses 0 are made up with only sufficient water to set up the cementitious binder and are formed and densely compressed in a suitable press. After drying out they form dense compact bodies or briquettes of uniform size which consist of approximately 85 percent of iron oxide.

($102). Si1i@a 2.70 (FeO)--- Ferrous oxide 52.11 (F8203) Ferric oxide 32.23 (A1203) Alumina. 1.04 (CaO) Lima 8.29 6.0 (MgO) Ma nesia 1.47 (MnO) .Manganous oxide .59 (P205) ..Phosphoric anhydride- .37 (H20) .Water 3.30

Specific gravity 3.722 5 These dense masses of bonded iron oxide provide in ideal form and condition an oxidizing agent which can be conveniently used in the open hearth process and which has the following ad- 7 vantages over even the high grade ore heretofore used, namely;

It is cheaper and universally available;

It is heavier than are and will more readily sink through the slag bath into the underlying 75 molten iron where it functions as a carbon reducer in an ideal manner and with a minimum of degradation;

It contains less impurities to contaminate the finished steel, such as phosphorus, silicon, etc., than does the highest grade hard ore available; and

Finally it can be produced in forms more convenient to handle and store, and which being of standard size, may be charged more accurately as to quantity.

The cementitious elements will bond the iron oxide so that it will not break up or disintegrate in the iron bath, but will be presented in a form which will attain the necessary carbon reducing action with the least possible disturbance of the open hearth furnace operation.

Where it has been attempted to use roll scale in loose form in open hearth furnace practice as a reducing agent, the reaction in the bath has been so violent and the evolution of gases so rapid that the light roll scale flakes are driven into the slag and out of the furnace with the gases. Its action is quick and violent and much less satisfactory than when controlled by bonding it into a dense mass, so as to retard its reducing action and hold it in the desired position, due to its specific gravity, in the iron bath.

The percentages and. components of the cementitious binder may be varied, but it is obviously 5 desirable to reduce same to the lowest percentage possible and to employ only substances which will have the least tendency to degrade the steel.

What I claim is:

1. An oxidizing agent for decarburizing open 110 hearth steel baths, comprising approximately 91 percent of roll scale, 3 percent of cement chemically inert with respect to the steel in the bath, and 6 percent of finely divided basic open hearth slag, compressed into dense permanently bonded briquettes.

2. A decarburizing medium for molten steel, consisting of a compressed block of from to 90% by weight of roll scale and the balance a binder of material chemically inert with respect to the steel consisting of substantially one part of cement to two parts of a filler of open hearth basic slag.

3. An oxidizing agent for decarburizing an open hearth bath, comprising approximately 90 parts of roll scale and 10 parts of a binder composed of approximately one-third a cement chemically inert with respect of the steel bath and twothirds a filler composed of finely ground slag derived from the open hearth process in which the oxidizing agent will be used, the whole being compressed before the cement sets into compact nonporous blocks substantially free of any elements which will disturb the chemical balance in the steel bath.

4. The method of producing a decarburizing block for use in the manufacture of steel for open hearth furnaces, which consists in combining approximately 90 parts of finely divided iron oxide with approximately 10 parts of a cementitious binder, the binder comprising approximately one part of cement, two parts of finely ground slag filler derived from the open hearth process, and approximately the theoretical quantity of water to combine with the cement and cause it to set, and compressing the block before it sets into a dense compact non-porous block.

MAURICE CARBERY SHANNON. 

